Is nicotine-free vaping safe? What the evidence actually shows

By Antonio Cappiello · Last reviewed 2026-09-25

No health authority treats it as safe. A 2025 systematic review of nine studies found nicotine-free e-cigarettes produced measurable short-term effects on blood vessels, including reduced flow-mediated dilation and increased arterial stiffness, and concluded they cannot be regarded as harmless. Long-term evidence does not yet exist.

What the question usually means

Most people asking this are not shopping for a new hobby. They are already vaping, they would like to use less nicotine, and a zero-nicotine device looks like a step in the right direction.

That is a reasonable instinct, and it deserves a straight answer rather than either a scare or a reassurance.

What a 2025 review found

The most direct evidence comes from a systematic review published in the Journal of Clinical Medicine in 2025 by Jukic, Becic, Matulic, Simac and Vukovic. They pooled nine studies: six human trials and three animal or embryonic models, all looking specifically at nicotine-free devices.

In the human trials they found:

Endothelial dysfunction, measured as reduced flow-mediated dilation, meaning blood vessels responded less well than they should
Increased arterial stiffness, with MRI studies documenting acute increases in aortic stiffness
Transient rises in blood pressure, which the authors describe as weaker, less predictable and shorter-lived than the equivalent effects from nicotine-containing products
No documented arrhythmias in the human trials, although animal models showed proarrhythmogenic potential

Across human and animal work they also found elevated reactive oxygen species and lipid peroxidation products, along with reduced nitric oxide availability. In plain terms: markers of oxidative stress went up, and a signalling molecule that keeps vessels relaxed went down.

Their conclusion, in their own words, is that nicotine-free e-cigarettes “cannot be regarded as harmless alternatives”, and that until longitudinal evidence clarifies the risk profile, a precautionary stance is appropriate.

A separate systematic review has looked at effects on the gastrointestinal system, reaching a similarly cautious position.

Why removing the nicotine does not empty the device

Take the nicotine out and three things remain: propylene glycol, vegetable glycerin, and flavourings.

Propylene glycol and glycerin are approved as safe for ingestion. That approval is about the digestive system. The lungs are not the digestive system, they have no equivalent body of evidence behind them, and a substance your stomach handles without difficulty is not automatically one your airways handle the same way.

Flavourings sit in the same position, and there are a great many of them. Each is a separate compound with a separate inhalation question that mostly has not been studied.

None of this means a nicotine-free device is equivalent to a nicotine one. The review’s own finding was that the effects were weaker and less predictable without nicotine. It means the honest description is “less, and not none”, rather than “safe”.

What is genuinely unknown

Worth being explicit, because the gaps matter as much as the findings.

Every human trial in that review measured acute effects, over minutes and hours. Nobody has followed nicotine-free vapers for twenty years, because the products have not existed for twenty years. When a review recommends a precautionary stance, that is what it is responding to: not evidence of long-term harm, but absence of evidence either way on a timescale that matters.

That cuts against confident claims in both directions. Anyone telling you these are proven safe is ahead of the data. So is anyone telling you they are proven dangerous over a lifetime.

The part this site can actually help with

There is one thing worth adding that has nothing to do with the chemistry.

Switching to a zero-nicotine device changes what you inhale. It does not change how often you reach for it. The reaching is the learned part, and it is the part that tends to outlast the chemical dependence by weeks.

If you are using a nicotine-free device as a step down, the number worth watching is not the strength on the label. It is how many times a day the device comes out, and whether that number is moving. Puff Counter counts each puff with one tap and shows the daily total and the hourly pattern. Counting is free, with no account and no ads.

That is a measurement, not a treatment. What to do about what you see is a conversation for you and a doctor or a stop-smoking service.

Count your own puffs

Puff Counter logs each puff in one tap and shows your daily pattern. Free on iPhone and Android.

Questions people also ask

Is nicotine-free vaping safe?

No health authority describes it as safe. A 2025 systematic review in the Journal of Clinical Medicine pooled nine studies and concluded that nicotine-free e-cigarettes cannot be regarded as harmless alternatives, recommending a precautionary stance until long-term evidence exists. The CDC's position is that no tobacco product, including e-cigarettes, is safe.

What did researchers actually measure without nicotine?

In the human trials covered by the 2025 review: acute endothelial dysfunction, reduced flow-mediated dilation and increased arterial stiffness, with MRI showing acute increases in aortic stiffness. Across human and animal models they found elevated reactive oxygen species and lipid peroxidation products, and reduced nitric oxide availability. Blood pressure rises were transient, and weaker and less predictable than with nicotine-containing products.

If it is just propylene glycol and glycerin, why would it do anything?

Because those ingredients are classed as safe to eat, not to inhale. Food-safety approval covers the digestive tract, and the lungs are a different organ with no equivalent evidence base. Flavouring compounds are a separate question again: they are also food-grade approvals, and the research on inhaling them is limited.

Is a zero-nicotine vape a good way to quit nicotine?

The evidence does not answer that question, and this is not medical advice. What the research does show is that removing the nicotine does not remove all the measured effects, and that the behaviour itself, the reaching and the inhaling, is the part that tends to outlast the chemical dependence. If you want a method with evidence behind it, a stop-smoking service or a doctor is the place to ask.

Is nicotine-free vaping safe in pregnancy?

There is no evidence base that would support calling it safe, and the systematic review above included animal and embryonic models showing effects without nicotine. Anyone who is pregnant or planning to be should take this to a midwife or doctor rather than to a web page, including this one.

Sources

This page is general information about vaping and nicotine, not medical advice. If you are worried about your health or want help quitting, talk to a doctor or a stop-smoking service.